Generally, a signal processing process of a transmission side for wireless communication is accomplished by channel coding, modulation, frequency up conversion, and transmission. Corresponding to this, signal processing of a reception side is accomplished by frequency down conversion, demodulation, and channel decoding. Here, the demodulation of the reception side includes a process of calculating a per-bit or per-symbol decoding metric. Generally, a Log Likelihood Ratio (LLR) is widely used as the decoding metric.
Generating the LLR requires premising a specific probability distribution for an interference and noise signal. To perform decoding with low complexity, the conventional art assumes a Gaussian distribution of an interference signal. Accordingly, to approximate a characteristic of the interference signal to the Gaussian distribution to the maximum, a modulation method of a Quadrature Amplitude Modulation (QAM) series is being mainly used. But, it has been widely known that a non-Gaussian channel has a bigger channel capacity than a Gaussian channel. Therefore, if decoding is properly performed, the non-Gaussian channel can provide greater decoding performance than the Gaussian channel.
According to this, there is a need for the development of a modulation method of enabling an interference signal to follow a non-Gaussian distribution.